The Electron Microscope Facility collaborates with Fox Chase Cancer Center investigators whose research requires high resolution information. The Facility offers a wide range of methods of sample preparation for the study of biological materials. These include negative staining, freeze drying/freeze fracturing-metal shadowing for viruses, vesicles protein particles and DNA molecules. For imaging of cells and tissues, room- and low-temperature embedding in various resins, thin sectioning of cell pellets/tissues and cells grown in a single layer, and serial sectioning are available as well as immunostaining of thin resin- or cryo-sections. Standard procedures of critical point- and air-drying combined with sputter coating are available for the scanning electron microscopy sample preparation. Depending on the nature of the information sought, the Facility suggests the experimental design, provides all the necessary reagents and, if needed, optimizes the approach. Due to the high specialization and labor intensity of the available methods, the Facility staff is typically solely responsible for the sample preparation, viewing, and image acquisition, and provides assistance in the interpretation of the results. Additionally, the Facility is modifying current methods and introducing new methods requested by FCCC investigators. During the current Core grant period, we introduced correlative microscopy which is now used by five peer-reviewed, funded investigators, and secured outside funding for a new, state-of-the-art electronoptical imaging system. In fiscal year 2003, the Facility was used by 10 peer-reviewed, funded investigators representing five research Programs from all three Divisions of the Center. Over 90% of Facility use was by peer-reviewed, funded investigators. Compared to 1998, the number of collaborators increased by 35%. In 2003, the Facility processed 180 samples, producing over 600 sample grids and documenting them on over 1,650 images. The Facility is equipped with two transmission electron microscopes, one of which houses a CCD camera, a scanning electron microscope, two microtomes equipped with cryoattachments, two metal evaporators, a low temperature embedding unit, and auxiliary equipment. While most data acquisition and image processing is performed digitally, a darkroom is available for developing negatives and enlarging prints.